According to CBS News, the school’s Principal Bo Ford sent a letter to parents apologizing for the incident. According to Ford, some of the instruments have covers that spell out the name of the school’s mascot, “Broncos” but for some reason, the letters c-o-o-n were placed together.

He also added that the covers are not normally worn on the field and said, the incident is “hurtful, disrespectful and disappointing.”